00:00
Welcome to this lecture on the spinal cord.
00:06
Our first slide depicts a lesion of the spinal cord.
00:10
This lesion is involving the dorsal columns/medial lemniscal system.
00:18
The lesion at this level within the spinal cord is affecting the first order neurons as they ascend
and this lesion then is ipsilateral
and as a result to this lesion being on the ipsilateral side of the pathway,
there will be an ipsilateral loss of function below this level of the lesion.
00:41
The loss of function would involve the loss of fine touch,
two-point discrimination,
loss of pressure and vibration senses,
as well as conscious proprioception
as these are the normal functions that are conveyed by this ascending pathway.
01:02
Here, you’re looking at a cross-section through the spinal cord.
01:07
And the lesion is depicted over here in the shaded light green area.
01:13
And so if we identify the lesion and the accompanying clinical features,
the lesion that’s a hemisection of the spinal cord as you see here
is referred to as Brown-Séquard Syndrome.
01:27
Brown-Séquard Syndrome
is gonna involve various aspects of the spinal cord,
the dorsal columns would be involved
in through here.
01:38
So again, this will be ipsilateral loss of fine structure,
two-point discrimination, vibration, pressure,
and conscious proprioception
at and below that particular level of the lesion.
01:54
The spinothalamic tracts are also involved here
and in this case, there will be a contralateral loss of pain and temperature
1-2 segments below the lesion,
and the reason that the loss of pain and temperature is 1-2 segments below the lesion
is due to Lissauer’s tract.
02:22
Lissauer’s tract, when the neurons, or at this level are ascending a couple of levels,
and so this is involving those levels that are below this particular level in the spinal cord.
02:36
Please note specifically that at level of the lesion, there is complete ipsilateral loss of all sensations.
02:45
Lastly, the corticospinal tracts are involved.
02:51
and at this particular level, there will be an ipsilateral paresis
at and below the lesion.
03:00
Here, we’re looking at a continuation of Brown-Séquard Syndrome.
03:07
In addition, to what we saw in the previous slide,
descending hypothalamics will be lesioned.
03:15
And so we lose the descending hypothalamic output.
03:18
And at this lesion is above spinal cord level T1.
03:23
The loss of sympathetics will result in ipsilateral Horner’s Syndrome.
03:29
So, miosis, anhidrosis, and ptosis
would be the triad of symptoms associated classically with Horner’s Syndrome.
03:42
Lower motor neurons would be involved here.
03:47
They would be damaged in the dorsal grey horn area
and as a result there will be flaccid paralysis at the level of the lesion.
04:00
And as it’s shown here, with paralysis, loss of muscle tone,
and just a general state of hypotonia.
04:09
Here, we’re looking at again a cross-section of the spinal cord
but this is a different lesion, or have a different set of clinical features.
04:25
Here, the lesion is, in this area of the cord, the posterior part.
04:30
So it’s involving the dorsal columns.
04:35
This particular lesion is referred to as Tabes Dorsalis.
04:42
And this disease is characterized by a slow degeneration,
demyelination of nerves
found primarily in these dorsal columns.
04:53
So, you have the fasciculus gracilis and the fasciculus cuneatus
ascending through this area of the spinal cord.
05:03
What are the accompanying clinical features of tabes dorsalis?
Individuals that have this lesion
complain of intense pain.
05:17
They complain of disturbed sensation.
05:23
and then usual high step gait.
05:30
There gait it is unsteady
and they will exhibit a positive Romberg’s sign,
which is demonstrated by a loss of balance when the patient has their eyes closed.
05:50
And this will be due to a loss of proprioception.
05:55
Due to disruption of proprioception, patients also exhibit sensory ataxia.
06:02
Sensory ataxia is characterized by an unsteady, stomping gait.
06:07
This is exaggerated when the eyes are closed.